Secondary CMB anisotropies from the kinetic SZ effect

Abstract

Abstract. The reionization of the universe by stars and quasars is expected to be a highly inhomogeneous process. Moreover, the fluctuations of the matter density field also lead to inhomogeneities of the free electron distribution. These patterns gave rise to secondary CMB anisotropies through Thomson scattering of photons by free electrons. In this article we present an analytic model, based on our previous work which tackled the reionization history of the universe, which allows us to describe the generation of these secondary CMB anisotropies. We take into account the "patchy pattern" of reionization (HII bubbles), the cross-correlations of these ionized regions, the small-scale fluctuations of the matter density field and the contribution from collapsed objects. For an open universe, we find that the angular correlation function C(θ) displays a very slow decline from C(0) ∼ 6 10 −13 up to the scale θ ∼ 10−3 rad where it shows a sharp drop. On the other hand, the power-spectrum l(l + 1)C l /(2π) (and the "local average" S l ) exhibits a plateau of height ∼10 −13 in the range 10 3 < l < 10 6 . We find that for large wavenumbers l > 10 4 the signal is dominated by the contribution from collapsed halos while for l < 10 4 it is governed by the large-scale correlations of HII bubbles. This implies that one cannot discriminate reionization by stars from a quasar-driven scenario since the size of ionized regions never dominates the behaviour of the anisotropies. Moreover, the secondary CMB anisotropies arise from a broad range of redshifts (7.5 < z < 10 for the IGM and 0 < z < 7 for galactic halos). Thus, we find that the generation of these anisotropies involves several intricate processes and they are close to the resolution limit of current numerical simulations. The signal expected in our model might bias the cosmological parameter estimation from CMB experiments such as Planck or MAP, and could be detected by future mm-wavelength interferometers (e.g., ALMA).

Implications of cosmological gamma-ray absorption

“…Salamon & Stecker (1998) and Pei et al (1999) discuss some of the possible effects caused by changes in the mean cosmic metallicity. The approximation of a fixed, high (solar) metallicity is motivated in part by structure formation simulations (e.g., Valageas & Silk 1999) which suggest that the mean metallicity in star forming regions is a slowly rising function for redshifts less than 2. The calculations of Valageas & Silk also indicate that the metallicity has been larger than 1/2 Z since z ∼ 2 (note that their estimate only includes enrichment due to SNII).…”

Entropy scaling in galaxy clusters: Insights from anXMM-Newtonobservation of the poor cluster A1983

“…However, there is little consensus regarding the source of this extra entropy. Pre-heating has been suggested (originally by Kaiser 1991 andHenry 1991), although there is no agreement on the astrophysical source responsible for it: early galactic winds (e.g., Loewenstein 2000), AGN (Valageas & Silk 1999), or possibly both. Other effects may also play a role, like radiative cooling (e.g., Muanwong et al 2001), or variation of galaxy formation efficiency with system mass (Bryan 1998).…”

Nonlinear Kinetic Sunyaev-Zeldovich Effect

“…Differences at high are likely due to simulation resolution and assumed ionization history. A model of inhomogeneous reionization in a distribution of bubbles [17] shares many features of the halo model but differs in details such as halo profile shapes and in the end leads to predictions about a factor of 10 smaller. This is perhaps due to both the cosmological model and assumptions about the distribution of ionized matter.…”